BIo 111 chpt 3 hw2-em

A fragment of DNA was found to have 45 adenine bases and 25 guanine bases. What is the total number of deoxyribose molecules in the molecule?

140

What facts would you select to show the major significance of the element carbon in the human body? Check all that apply.

Carbon has four valance electrons. Carbon forms the backbone of all organic molecules. Carbon can form bonds with four different atoms. Carbon can from four covalent bonds with another carbon atom.

Macromolecules that are used by most organisms to store hereditary information are called:

DNA molecules.

What is the difference in the bonding between alpha-helix and beta sheets?

Hydrogen bonding occurs between the amides of adjacent chains in the sheets instead of between the amides in different parts of the helices.

The structure of chlorophyll is shown below. Based on this structure, where would you predict that it would be found in a cell?

In a membrane because it has a hydrophobic tail and a polar head.

What functional groups are present on this molecule? Check all that apply.

carboxyl hydroxyl amino

Lipids are the only class of macromolecules that contain:

fatty acids.

Organic molecules have a carbon backbone and _____ such as -OH and -NH2 that affect their chemical properties.

functional groups

The simplest and the most common monosaccharide is a six-carbon sugar called:

glucose.

Macromolecules are broken down to monomers in ___

hydrolysis reactions

These biological compounds are non-polar and insoluble in water:

lipids

Carbohydrates are polymers formed of structural units called:

monosaccharides.

The information storage molecules of cells are called:

nucleic acids.

Biological membranes contain bilayers containing mostly ______.

phospholipids

Amino acids are linked together by peptide bonds in a ____

polypeptide.

Common lipids for energy storage are:

triglycerides

The nitrogenous base that is only found in RNA and not DNA is

uracil

The covalent bonds connecting monomer units in sugars can be formed by the removal of a water molecule. This reaction is referred to as:

a dehydration reaction.

Chitin, a modified form of cellulose, is not only cross-linked with proteins but its glucose units are modified with atoms of:

nitrogen

Gout is caused by deposition of uric acid crystals in joints. It results from the metabolic breakdown of purines, which are found in many foods and are part of normal human tissue. Traditionally, doctors have recommended that people with gout avoid or limit consuming foods that are high in purines. Based on this information, which macromolecule that is naturally found in the human body would be most problematic for these patients?

nucleic acids

What levels of protein structure would be affected if all hydrogen bonding interactions were prevented? Check all that apply.

secondary tertiary quaternary

A cell with 24% guanine would have how much adenine?

26%

In Alzheimers disease patients develop amyloid plaques that contain misfolded beta-amyloid proteins. Based on this observation you would predict that:

The misfolded beta-amyloid proteins could not be refolded by chaperone proteins

Phospholipids are important molecules in cells. Considering the structure and function of phospholipids, check all statements that apply.

They contain a glycerol backbone. The phosphate head group is polar. The molecule is an important part of cell membranes.

Fats are excellent energy storage molecules because:

they have a relatively high ratio of energy storing C—H bonds.

Indicate whether each of the following statements about protein structure is true or false. f= 1,3,5

1. A distinctive and recurrent sequence of structural elements within a protein, such as helix-turn-helix, is called a domain. false 2. Many proteins are composed of several different regions that are specialized to carry out specific functions. true 3. Specific functional regions within a protein are called motifs. false 4. As a polypeptide chain folds, each domain takes its proper shape more or less independently of the others. true 5. If we replace one domain of a protein with a domain from a different protein using molecular biology techniques, then the entire protein will become inactive. false

Indicate whether each of the following statements about triglycerides is true or false. f= 1,3,4,7,8

1. A triacylglycerol is composed of 3 glycerol molecules joined to a fatty acid. false 2. The fatty acids of a triglyceride need not be identical, and often they are very different from one another. true 3. Glycerol is a three-carbon alcohol, in which each carbon bears a carboxyl group. false 4. A fatty acid consists of a hydrocarbon chain joined to a hydroxyl group. false 5. The hydrocarbon chains of fatty acids vary in length as well as in the number and location of double bonds between the carbon atoms. true 6. Fatty acids with one double bond in their hydrocarbon chain are called monounsaturated, while those with more than one double bond are called polyunsaturated. true 7. A saturated fatty acid has the maximum number of oxygen atoms bonded to its hydrocarbon chain. false 8. Fats containing unsaturated fatty acids have high melting points because their fatty acid chains bend at the double bonds, preventing them from packing closely together. false 9. Most plant fats contain saturated fatty acids and are therefore liquid at room temperature. false 10. Additional hydrogen atoms can be added to saturated fats, a process called hydrogenation. false 11. When unsaturated fats are partially hydrogenated industrially, this can produce trans fats which have been linked to elevated levels of low-density lipoprotein (LDL) "bad cholesterol" and lowered levels of high-density lipoprotein (HDL) "good cholesterol." true

Match the following molecules with their function.

1. DNA Contain genes that can be transcribed 2. mRNA Translated into proteins 3. ATP Provide energy for cell activities 4. NAD+ and FAD Transport electron

Indicate whether each of the following statements about protein structure is true or false. f=1,3,4,6,10,11

1. If a protein's environment is altered, the protein may change its shape or even unfold completely, a process called dissociation. false 2. Proteins can denature when the pH, temperature, or ionic concentration of the surrounding solution changes. true 3. Denatured proteins are usually biologically active. false 4. When normal environmental conditions are reestablished after protein denaturation, almost all proteins can spontaneously refold back into their natural shape. false 5. If the 3-D structure of a protein depends only on its primary structure and the surrounding environmental conditions, then when the protein is denatured and subsequently returned to its native conditions it will spontaneously refold back into its native structure. true 6. Proteins have a narrow range of conditions in which they fold properly; outside that range, proteins tend to renature. false 7. Some proteins require other proteins called chaperones in order to correctly fold into their normal 3-D shape. true 8. Cells use chaperones both to accomplish the original folding of some proteins and to restore the structure of incorrectly folded ones. true 9. Some diseases may occur because a protein with the correct amino acid sequence fails to correctly fold into its final functional form. true 10. During a process called dissociation, the polypeptides of a protein with quaternary structure separate and unfold, losing their individual tertiary structure. false 11. The final 3-D shape of a protein is determined entirely by its primary structure. false

Indicate whether each of the following statements about polysaccharides is True or False. f=1,2,5,7,8,9

1. Polysaccharides are long polymers made of many nucleotides that have been joined through dehydration synthesis. false 2. Cellulose is the main storage polysaccharide in plants while glycogen is an important storage polysaccharide in many animals. false 3. Both starch and glycogen are composed of α-glucose subunits. true 4. Starch is composed of amylose and amylopectin, which are unbranched and branched chains of α-glucose subunits, respectively. true 5. Like amylopectin, glycogen is insoluble in water, but it has a longer average chain length and fewer branches. false 6. Although some polysaccharides are used to store energy, others serve as structural material for cells. true 7. The principal structural polysaccharide in plants is starch. false 8. Cellulose is composed of a long, branched chain of β-glucose subunits. false 9. The starch-hydrolyzing enzymes produced by most organisms cannot break the bond between two α -glucose subunits because they only recognize β linkages. false 10. Chitin is a structural polysaccharide found in the exoskeleton of arthropods and the cell wall of many fungi. true

Indicate whether each of the following statements about nucleic acids is true or false. false= 1,3,6,7,11

1. The 2 types of nucleic acids found in living organisms are ribose and deoxyribose. false 2. The replication of DNA allows living organisms to pass on the code for making proteins from one generation to the next. true 3. DNA differs from RNA because it contains the sugar deoxyribose instead of ribose, it has the base uracil instead of thymine, and it is double-stranded rather than single stranded. false 4. Nucleic acids are long polymers of repeating subunits called nucleotides. true 5. Each nucleotide consists of three components: a pentose sugar, a phosphate group, and a nitrogenous base. true 6. When 2 nucleotides join by a condensation reaction, the phosphate group of one nucleotide binds to the nitrogenous base of the second nucleotide, forming a phosphodiester bond. false 7. A polynucleotide chain has a phosphate group at the 3´ end and a hydroxyl group at the 5´ end. false 8. During protein synthesis, the sequence of bases in RNA controls the sequence of bases in DNA which, in turn, controls the sequence of amino acids in a polypeptide. false 9. In DNA, adenine always pairs with thymine and guanine always pairs with cytosine. true 10. DNA is used to store the information needed to make all proteins required by an organism and to pass that information on to the next generation. true 11. In order to make a protein, information stored in RNA must be transcribed into molecules of DNA which directs the synthesis of proteins. false

Carbohydrates are used in cells for structural purposes and as an energy source. What is the main type of carbohydrate contained in each of the following? 1. Potato as food 2. Fruit as food 3. Stored human energy 4. Human blood sugar.

1. starch 2. fructose 3. glycogen 4. glucose

Which fatty acid has the highest melting point?

20 carbon chain with no double bonds

A candy bar contains 108 calories per serving. There are 4 grams of carbohydrate, 5 grams of protein, and 8 grams of fat in a serving. How many of the calories come from fat?

72

Match the appropriate functional groups to the physical and chemical properties described. 1. Phosphate group 2. Carboxyl group 3. Hydroxyl group 4. Amino group 5. Methyl group 6. Sulfhydryl group

Nonpolar, hydrophobic, found in hydrocarbon chains.Correct: 5 Polar, soluble, forms H bonds, forms alcohols+=3 Polar, soluble, protons can dissociate from this group and it has acidic properties.=2 Polar, soluble, can act as a weak base and can accept a proton.=4 Polar, soluble, can participate in bonds that are important in energy storage, can be acidic if it loses protons.=1 Stabilizes proteins.=6

Mutations that lead to the translation of a protein with an altered primary sequence can sometimes lead to problems within the cell. As one example, in sickle cell disease, patients contain a mutation in the gene for hemoglobin that converts Glutamic Acid into a hydrophobic amino acid. Hemoglobin is the protein that carries oxygen in our red blood cells. As a consequence of this amino acid substitution, hemoglobin molecules tend to aggregate when they are not bound to oxygen. The aggregation of the hemoglobin protein causes the red blood cells to deform into the characteristic sickle-cell shape. These deformed red blood cells become trapped in small capillaries, leading to many of the symptoms of this disease. What amino acid do you think that Glutamic Acid could be converted to in order to cause Sickle Cell Anemia?

Valine

Below are a series of monomer-polymer pairings. Choose the pairings that correctly match the monomer constituents with the polymers they form. Select all that apply.

monosaccharides : carbohydrates nucleotides : DNA fatty acids, glycerol : triglycerides 4 carbon rings : steroids